An elevator cab assembly will typically comprise a passenger cab which is mounted in a rectangular frame. The cab assembly moves up and down in the elevator hoistway along guide rails which are mounted on opposite walls of the hoistway.
Japanese Kokai Publication No. 3-23185, published Jan. 31, 1991, discloses a system for stabilizing an elevator cab as it is moving along guide rails in a hoistway, which guide rails possess a varying compliancy. The system includes transverse beams above and below the cab assembly. Rail guides are mounted on the ends of the transverse beams by means of vibration-proof rubber pads. The beams are also connected to the cab assembly by vibration-proof rubber pads. A contoured guide piece is fixed to the hoistway wall which mimics the compliancy values of the rails, and contact sensors are mounted on the beams to slide over the guide piece. Motion of the contact sensors is monitored by a control which operates actuators operable to laterally shift the beams in response to movement of the contact sensors. The rail guide will thus be moved laterally relative to the cab assembly as the rail compliancy varies. A problem found in this teaching concerns the fact that if the beam is moved to the left to shift the left-hand rail guides in response to variations in compliancy of the left-hand rail, then the right-hand rail guides must necessarily move in the same direction as the left-hand rail guides. The objective of moving the rail guides toward a rail as rail compliancy increases, and away from the rail as rail compliancy decreases is thus only attainable on one of the rails, and the opposite rail guide movement occurs at the other opposite side rail. The use of the guide piece is also cumbersome, and its ability to mirror rail compliancy is problematic, at best. Kokai 3-51280, published 5 Mar. 1991, shows other aspects of the same system.
Another approach shown in Kokai 3-51279, published 5 Mar. 1991, uses actuable horizontal ropes strung on pulleys from corner to corner on diagonals across the cab's roof and converging at a point above the cab to control the tilt of the cab.